Effects of Blue-light Blocking Lens on Visual Functions

February 23, 2017 updated by: The Hong Kong Polytechnic University

Working Hypothesis: The blue-light blocking lens has no effect on the contrast sensitivity, accommodative response, color vision, and subjective grading of the quality of life and vision.

Purpose: To determine and compare the visual performances after wearing the blue-light blocking lenses in participants with and without presbyopia.

Methods: One hundred and sixty computer users (computer usage >2 hours/day) with (n=120, aged >40years) and without presbyopia (n=40, aged 18-35 years) will be recruited. Three pairs of ophthalmic lenses will be prescribed for the participants, in which one pair of them will be the blue-light blocking lenses (StressFree, Swisscoat, HK). The lenses will be used for intermediate vision (i.e., computer usage) in presbyopic group, and for distant vision in non-presbyopic group. The adaptation period for each pair of lenses will be 1 month. The pre- and post-treatment contrast sensitivity, accommodative response and color vision will be measured. The participants will also be asked to complete questionnaires about their quality of life and vision, and the performances of these ophthalmic lenses.

Significance: The blue-light blocking lens reflects the short-wavelength lights and protects the retina from "blue-light hazards"; however, blue lights are essential for various visual function and circadian rhythms. This study will evaluate the impact of the blue-light blocking lenses on visual function and quality of life, and determine whether the blue-light blocking lenses are good choices for extra ocular protection.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Actual)

80

Phase

  • Not Applicable

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 55 years (Adult)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • age: 18 to 35 years OR 40 to 55 years
  • daily computer usage over over 2 hours per day

Exclusion Criteria:

  • visual acuity worst than 0 logMAR
  • abnormal binocular and color vision
  • previous history of ocular surgeries

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Other
  • Allocation: Non-Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Young adults
adults without presbyopia who aged 18-35 years
Device: clear lens with regular coating
Device: regular coating lens with yellow tint
Device: clear lens with blue-light blocking coating
Experimental: Middle-aged adults
adults with presbyopia who aged over 40 years
Device: clear lens with regular coating
Device: regular coating lens with yellow tint
Device: clear lens with blue-light blocking coating

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Contrast Sensitivity as Assessed by Mars Contrast Sensitivity Chart
Time Frame: Every 1-month interval from the date of randomization, up to 3 months

Contrast sensitivity was measured using the Mars contrast sensitivity letter chart (Mars Perceptrix, Chappaqua, NY). One out of three charts differing in the letter combinations was selected randomly in order to avoid memorization of the charts. The chart was placed at 50 cm with each letter subtended 2° visual angle. We followed the recording procedures as specified by the manufacturer: participants were instructed to read the letters from high to low contrasts and the test ended when two consecutive errors were made. The contrast sensitivity was scored as the log contrast sensitivity of the last correct letter minus 0.04 log unit for every prior error. The test was administered under normal (room illumination, 400 lux) and glare conditions. A brightness acuity tester set at its medium light intensity level (100 foot lamberts) simulated the glaring condition.

A higher mean indicates improved contrast sensitivity.
Every 1-month interval from the date of randomization, up to 3 months
Color Vision as Assessed by the Farnsworth Munsell 100 Hue Test
Time Frame: Every 1-month interval from the date of randomization, up to 3 months

The Farnsworth Munsell 100 hue test (X-Rite, USA) was used to evaluate colour vision. Each of the four trays consisted of 21 movable caps. Participants were asked to sort the randomly arranged caps following the hue order from the first to the last fixed caps. The total error score was calculated, as documented in the instruction manual, to quantify the accuracy of color discrimination.

There are no defined endpoints to the "total error score" range.

A lower score indicates improved color discrimination ability.
Every 1-month interval from the date of randomization, up to 3 months

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Self-assessment of Lens Performance Through Questionnaire
Time Frame: Every 1-month interval from the date of randomization, up to 3 months

After each monthly wearing period (visits 3-5), the participants' lens performance, night vision quality and sleep quality (total 13 questions) were assessed subjectively using a questionnaire (scoring from 1 [very unsatisfactory] to 5 [very satisfactory]).

At the end of the study, the participants were asked to choose their preferred lens type among the three pairs of lenses based on their subjective feeling of the "best lens type" (i.e., either clear lens, yellow tinted lens or blue-filtering coated lens).

To make it clear and simple, here we only present the data on the participants choice of their preferred lens type (i.e., simply choosing the "best lens" among clear lens, yellow tinted lens or blue-filtering coated lens).
Every 1-month interval from the date of randomization, up to 3 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

The Hong Kong Polytechnic University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

July 1, 2014

Primary Completion (Actual)

May 1, 2015

Study Completion (Actual)

May 1, 2015

Study Registration Dates

First Submitted

June 27, 2016

First Submitted That Met QC Criteria

June 29, 2016

First Posted (Estimate)

July 1, 2016

Study Record Updates

Last Update Posted (Actual)

April 7, 2017

Last Update Submitted That Met QC Criteria

February 23, 2017

Last Verified

June 1, 2016

More Information

Terms related to this study

Other Study ID Numbers

  • HSEARS20140512001-03

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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